// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_MESSAGE_LOOP_MESSAGE_PUMP_GLIB_H_
#define BASE_MESSAGE_LOOP_MESSAGE_PUMP_GLIB_H_

#include <memory>

#include "base/base_export.h"
#include "base/macros.h"
#include "base/message_loop/message_pump.h"
#include "base/observer_list.h"
#include "base/time/time.h"

typedef struct _GMainContext GMainContext;
typedef struct _GPollFD GPollFD;
typedef struct _GSource GSource;

namespace base {

// This class implements a base MessagePump needed for TYPE_UI MessageLoops on
// platforms using GLib.
class BASE_EXPORT MessagePumpGlib : public MessagePump {
public:
    MessagePumpGlib();
    ~MessagePumpGlib() override;

    // Internal methods used for processing the pump callbacks.  They are
    // public for simplicity but should not be used directly.  HandlePrepare
    // is called during the prepare step of glib, and returns a timeout that
    // will be passed to the poll. HandleCheck is called after the poll
    // has completed, and returns whether or not HandleDispatch should be called.
    // HandleDispatch is called if HandleCheck returned true.
    int HandlePrepare();
    bool HandleCheck();
    void HandleDispatch();

    // Overridden from MessagePump:
    void Run(Delegate* delegate) override;
    void Quit() override;
    void ScheduleWork() override;
    void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;

private:
    bool ShouldQuit() const;

    // We may make recursive calls to Run, so we save state that needs to be
    // separate between them in this structure type.
    struct RunState;

    RunState* state_;

    // This is a GLib structure that we can add event sources to.  We use the
    // default GLib context, which is the one to which all GTK events are
    // dispatched.
    GMainContext* context_;

    // This is the time when we need to do delayed work.
    TimeTicks delayed_work_time_;

    // The work source.  It is shared by all calls to Run and destroyed when
    // the message pump is destroyed.
    GSource* work_source_;

    // We use a wakeup pipe to make sure we'll get out of the glib polling phase
    // when another thread has scheduled us to do some work.  There is a glib
    // mechanism g_main_context_wakeup, but this won't guarantee that our event's
    // Dispatch() will be called.
    int wakeup_pipe_read_;
    int wakeup_pipe_write_;
    // Use a scoped_ptr to avoid needing the definition of GPollFD in the header.
    std::unique_ptr<GPollFD> wakeup_gpollfd_;

    DISALLOW_COPY_AND_ASSIGN(MessagePumpGlib);
};

} // namespace base

#endif // BASE_MESSAGE_LOOP_MESSAGE_PUMP_GLIB_H_
